Effect of microstructure on fatigue life and fracture morphology in an aluminum alloy

The effect of grain refinement on the fatigue life of 7075Al alloy was evaluated using a subsize fatigue specimen. High-cycle fatigue of fine-grained 7075Al showed substantial improvement over the parent 7075-T6 material. This improvement in fatigue life is ascribed to retardation of crack propagation caused by grain boundaries acting as barriers and a crack closure effect due to crack deflection.